This project will attempt to define the clinical significance of granulocyte specific antigens and antibodies. Antibodies will be detected using granulocyte cytotoxicity, immunofluorescence, radioactive staphylococcal protein A, lymphocyte cytotoxicity, and enzyme-linked immunoassay. The serology of these antibodies will be investigated by characterizing the immunoglobulin class of antibody involved and by determining the antigen specificity of the antibody. Patients who have antibodies reactive in one or a unique combination of these assays will be selected for study. Patients will receive injections of Indium-111-labelled granulocytes, both compatible and incompatible by the serologic technique. The in vivo fate of injected granulocytes will be studied by measuring the intravascular recovery and half life by total body scanning for localization of granulocytes and sites of infection and by measuring migration of granulocytes into a skin window.